1. The Field of the Invention
The present invention relates generally to Geographic Information Systems (GIS). More specifically, the present invention relates to collaborative environments in GIS.
2. The Relevant Technology
Geographic information systems are widely used in areas such as commerce, government defense, environmental research, and academic research. These systems are tools that allow for the processing of spatial data into information typically tied explicitly to, and used to make decisions about, some portion of the earth (i.e. geo-spatial data). Geographic information systems can deal with space-time data and often employ computer hardware and software (i.e. executable instructions) for storage, manipulation, analysis, and presentation of the data to a user.
Many aspects of current GIS modeling are based at least in part on traditional cartography. In traditional cartography, the cartographer compiles or records a map made up of points, lines, and areas on a physical medium, such as paper. Data can be collected from such sources as aerial photography, digital remote sensing, surveying, visual descriptions, and census and statistical data. In GIS, data collection sources include the same sources as those used for traditional mapping, but can also include a wide variety of digital sources, such as digital line graphs (DLGs), digital elevation models (DEMs), digital orthophotoquads, digital satellite imagery, as well as many others.
Various computer hardware and software components can be implemented to manipulate and analyze the data collected. Queries of GIS data storage and retrieval device can be made and context-specific information can be recalled along with image data for analysis. GIS analysis device can analyze the geo-spatial data to compare and contrast patterns of earth-related phenomena. Geographic information system analysis can use computers to measure, compare, contrast, and describe the contents of the databases. Analysis of the data can also permit aggregation and reclassification for further analysis.
GIS have many advantages over the graphic map in that queries can be made of the data and only the desired context-specific information recalled. In general, GIS store the graphic locations of point, line, and polygon objects and their associated characteristics (attributes). This format emphasizes formulating queries and asking the appropriate questions, rather than overall map interpretation.
GIS model can include raster and/or vector models. A raster data model represents spatial data as a matrix of pixels. The raster data model, in essence, consists of values for each pixel on a computer monitor. The pixels are lit up via a raster scan, which is a technique for generating or recording the elements of a display image by means of a line-by-line sweep across an entire display space. In contrast to the raster data model, a vector data model is an abstraction of the real world in which elements are represented in the form of points, lines, and polygons. Objects can be displayed along with (e.g., can overlay) vector and raster data. Object can refer to anything with object attributes, where object attributes are attributes characterizing at least part of an object to be displayed, such as area of a surface or footprint, longest single dimension, or a volume. An object can be a building, for example. A building can have overlaid raster (e.g. to provide color for the roof), texture (e.g. to create windows and bricks on a side of the building), or height data. An object can also include vector data representing, for example, a road, fire hydrant, etc.
Using the building blocks of rasters and vectors, GIS can be used to analyze land based activity, such as ownership or management of land, habitat evaluation, conservation easement procurement, wildlife evaluation, earthquake and landslide prediction, flood hazard abatement, chemical contamination evaluation, forest and range management, scientific investigation, as well as many other applications. For such varied applications of GIS, large amounts of data typically must be accessed and processed. In systems in which GIS data is transmitted over a network, such as the Internet, data transmission latencies can limit the effectiveness of geographic information systems and the amount of resolution that can be reasonably displayed. GIS data also often requires editing by GIS processors, which can complicate access to the GIS data and the edits made by the GIS processors. It may be advantageous for multiple users to collaborate on such analysis and editing. Thus, it would be advantageous to improve streaming objects in GIS, which would enhance the ability to use networked geographic information systems and improve the quality of the displayed data. Further, there is a need for improved collaboration between GIS processors for analysis and editing.